On 11/2/21 3:01 PM, Lux, Jim wrote:
On 11/2/21 11:41 AM, Mpridesti via TowerTalk wrote:
My 80 m 4 SQ seems to work well in 3 positions. To the SW the signal
drop in the favored direction where the other 3 directions appear to
work well.
SWR measurements seem normal around 2:1 at the end of the 1/4 wave 75
ohm lines except one which is 1.87. Haven’t made loss measurements
yet but I suspect the lowest SWR line is the problem (low reading due
to higher than normal loss making it the suspect line).
Has anyone else experienced this type of behavior? Also the suspect
line is the NW element and the direction which has the problem is SW.
Does this make sense? Effectively this lossy element is the other
half of the “driven element “ if you thought of the 4 sq as a 3 el
vertical beam.
Keeping with this concept, one would think the NE direction would
have similar loss but it doesn’t (or it’s not noticeable).
This is where a NanoVNA might be a useful tool. Not only can you go
out to the box and measure each element separately, but you could
measure the element to element coupling, and I'll bet you'd see
something.
You *might* be able to do a sweep from the shack, through the box, and
figure something out too, but figuring out which of the 4 has a
problem - I guess you could switch the direction of the beam and
probably figure it out.
FWIW TDR (from a sweep) would definitely show a lossy cable or element.
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